Electrodes of vitreous carbon are suitable for use as implantable effectors, and as sensors for use in biomedical applications. See, e.g., DE-OS No. 26 13 072. Effectors are intended herein to refer to electrodes through which a stimulating effect is produced; sensors are electrodes with which measurements may be conducted. Examples of effectors are stimulating electrodes for cardiac pacers, as well as electrodes employed to stimulate nerves and muscles. Electrodes employed to make oxygen measurements in the body are referred to herein as sensors.
For implantable electrodes which consist generally of an electrode head and an electrode stem the following requirements are of particular importance and must be met:
Good body compatability, PA1 High capacity and, therefore, low polarization, PA1 Low chronic stimulation threshold rise. Electrodes of vitreous carbon satisfy the two first-mentioned requirements quite well. However, they display a long-term rise in stimulation threshold.
One possible explanation for the rise in stimulation threshold observed in vitreous carbon electrodes is the rough surface of such electrodes. This roughness is caused by the mechanical processing in the manufacture of the electrodes. The present method employed during the manufacture of stimulation electrodes of vitreous carbon consists of the chip-removing shaping of a blank of cross-linked synthetic resin and the subsequent pyrolysis of the electrode body obtained. In addition, the foregoing method is cost-intensive.
It is an object of this invention to provide a simple and inexpensive method which permits the manufacture of implantable electrodes of vitreous carbon which meet all of the requirements for such electrodes specified above.